I've got a bunch of application CDs that I use here at home under Wine. They are Windows applications and as such, some of them want to see the volume label in order for the application to run. So... just copying the CD-ROM contents to a directory doesn't work. With that in mind, what I've done in the past is make ISO images of the CD-ROMs on my hard drives and mount them locally. The mounted device is then mapped to "Drive D:" in Wine. This has always worked well. But I wanted to prevent wasting HD space on my clients, so I centralized the ISOs on a server. Until now, I've been using Samba to share those ISOs but seeing that I no longer have any Windows boxes, I've been moving away from Samba and onto NFS. However, I now have a problem. If I mount 'server:/mnt/data/cdserv' on /mnt/data/cdserv on the client, I can see my ISO images. No problem. But when I try to mount one of those ISO images to /mnt/cdrom1. I get a "permission denied" error.
While testing, I tried to manually associate /dev/loop0 with /mnt/data/cdserv/abh12.iso and I got the same "permission denied" error. So it sounds like the process fails when setting up a loop device. What is odd is that iso9660 is a read only file system. I have the NFS server exporting 'ro' and the export is mounted 'ro'. So my guess is that the "permission denied" error is being caused by the loop set up and nothing else. Any ideas why? Do I need to use a special option with losetup if I set the loop device up manually? Or is it an NFS export or mount issue? Is there some aspect of the ISO image that's not getting carried over NFS? This worked very well for me under Samba, but I really don't need Samba anymore and would hate to keep it around for just this one application.
One more thing I just discovered. I created a looped ext2 filesystem image and put it in the same location that my ISOs are. I tried to mount it via nfs as a loop device and got the same "permission denied" error. So it definitely seems that losetup/loop devs don't like to be exported via NFS. I'm still not sure why though since NFS seems to act like a normal filesystem in every other regard. Still searching for an answer...